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Old 1st October 2012, 04:06 PM   #1
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Default how to get more Bias current from LME49811?

looking to build a class A amp with LME49811 since its output current is pretty much limited. How to get more bias current from the LME49811? Is there any schematic for this?
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Old 1st October 2012, 04:48 PM   #2
sreten is offline sreten  United Kingdom
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Quote:
Originally Posted by rhythmsandy View Post
looking to build a class A amp with LME49811 since its output current
is pretty much limited. How to get more bias current from the LME49811?
Is there any schematic for this?
Hi,

The devices bias current capability is not related to the class A
standing current in the output devices or the standing current
in the output devices for correctly biased class aB.

The device should provide a constant current of 5mA to 10mA
to bias the Vbe multiplier and this will be correct irrespective
of the mode of operation of the output stage.

The unity gain output stage needs enough current gain for the
Vas current to be sufficient to drive it, again independent of
class A or class aB (or class AB, e.g. class A up to 1/4 power).

There is no logic in saying the device needs a class A output.

rgds, sreten.

Note the application data does not detail output protection.
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Last edited by sreten; 1st October 2012 at 04:54 PM.
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Old 1st October 2012, 05:00 PM   #3
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is there any schematic for Class A using LME49811?
how about BJTs vfs HEXFETs ? how does the sound quality varies. I came to know that some of my friends say HEXFET sound better... I understand the implementation aspect but overall which is chosen when sound quality comes?
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Old 1st October 2012, 08:04 PM   #4
sreten is offline sreten  United Kingdom
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Hi,

If you don't ask the right questions you will never get the right answers.

e.g. for the first loads if you understand what it is designed to replace.

rgds, sreten.
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There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

Last edited by sreten; 1st October 2012 at 08:08 PM.
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